Film strip advancing mechanism for projectors



Dec. 8, 1953 l. R. BAHGBERGH FILM STRIP ADVANCING MECHANISM FOR PROJECTORS Filed April 3, 1951 ATTORN EY Patented Dec. 8,

FILM STRIP ADVANCING MECHANISM FOR PROJECTORS Lester Raymond Bangsbergh, Dobbs Ferry, N. Y.. assigner to Harvey T. Mann, New York, N. Y.

Application April 3, 1951, Serial N0. 219,076

9 Claims. l

The present invention relates to projectors, and, more particularly, relates to projectors of the type for projecting photographic image bearing strips of nlm provided with a plurality of frames each having an opening associated therewith for cooperation with mechanism for advancing the strips.

Accordingly, an object of the present invention is to provide such a projector having film strip advancing mechanism which is simple and economical in construction and is accurate and reliable in operation.

Another object is to provide such mechanism having an element cooperating with the lm strip opening for advancing the film strip which element is self indexing regardless of the position of the openings when the nlm strip is initially inserted into the projector.

Another object is to provide such mechanism which will not damage the film strip.

Another object is to provide such a projector having an improved guideway for the lm strip.

Another object is to provide such a guideway which maintains the film strip frames perfectly fiat at the plane of projection but permits the nlm strip to be moved freely therethrough whereby the emulsion on the lm is not damaged.

A further object is to provide such a guideway which is adapted to accommodate film strips of different lengthwise dimensions.

Other and further objects will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the present invention, the foregoing objects are generally accomplished by providing a projector comprising in combination a guideway for a strip of lm which has an opening associated with each frame thereof, a member slidably mounted adjacent the guideway for movement longitudinally with respect thereto and having a pair of spaced stops, a lever pivotally mounted on the member having an arm positioned between the stops and having a second arm formed with an end portion for extending into the frame openings, and manually operable means for rocking the lever and effecting sliding movement of the member upon engagement of one of the stops of the first mentioned arm.

In a preferred embodiment of the invention about to be described, the slidable member is maintained adjacent the guideway by resilient 2 means which are adapted to yield while the lever portion is seeking a frame opening during initial operation in cases where the film strip when inserted was not indexed with the advancing mechanism, whereby the film strip will not be nicked or torn.

The guideway includes a spacing means of a thickness slightly greater than the film strip to form a passageway through which the lm strip is advanced, and includes spring urged transparent plates at the point of projection for maintaining the film strip smooth and flat, which plates are spaced apart by the aforementioned spacing means. Interchangeable frames are associated with the plates for accommodating lm strip frames of different lengthwise dimensions.

A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawing, forming a part of the specification, wherein:

Fig. l is a fragmentary side elevational View of a projector embodying the invention.

Fig. 2 is a front view of the projector shown in Fig. 1.

Fig. 3 is an enlarged sectional view taken substantially along the line 3-3 on Fig. 1 illustrating the film strip advancing mechanism in elevation.

Fig. 4 is a sectional view taken along the line 4-4 on Fig. 3 with the film strip advancing element shown in its at rest or normal position.

Fig. 5 is a fragmentary enlarged sectional view with the lm strip advancing element shown in the position it assumes upon initial actuation.

Fig. 6 is a view similar to Fig. 5 with the film strip advancing element shown in the position it is moved at the completion of the lm advancing stroke.

Fig. '7 is a fragmentary enlarged sectional view taken along the line 1,--1 on Fig. 3.

Fig. 8 is a fragmentary enlarged sectional View taken along the line 8'-8 on Fig. 3 illustrating details of the lm strip guideway.

Referring to the drawing and more particularly to Figs. 1 and 2 thereof, there is shown a projector of the character previously indicated herein which comprises a light source housing IU of conventional design, a guideway assembly Il for a film strip S mounted on the front wall I2 of the housing, a lens assembly I4 mounted on the front of the guideway assembly, and lm strip advancing mechanism of which only an operating handle I5 and handle adjusting knob I6 are shown in these views.

As illustrated in Figs. 3 to 8, the Wall I2 has a rectangular opening I1 at the point of projection through which a beam of light is adapted to pass and has a vertical slot I9 just below the opening I1 for receiving an element of the lm strip advancing mechanism, to be described hereinafter. A vertical slot 2U is provided in the side wall of the housing adjacent the rear of the wall |'2 through which the handle I5 extends.

The guideway assembly comprises a pair of superimposed body members 2| and 22, the member 2| being secured to the iront wall I2 of the housing and the member 22A being removably attached to the member 2| (Figs.` 1" and 4f to` 8e); These members are formed with an opening 24 and 25, respectively, in alignment with the light beam opening Il and each other, theopening being somewhat smaller (Fig. 8v). As best shown in Figs. to 7, the member 2| has a vertical slot 26 adjacent the slot I9 for the reception ofa recessl 2l facing the slot 2,6.

frAjpassageway for the nlm strip isv provided between'the members 2| and 22 byvrneanjsv of a pairof paralleLspaced apart relatively thin'v strips secured to" the member 2I yby meansoiscrews 30 or'\t1'ie` like"(Figs. 7 and 8).v Theselstrip's have a thickness slightly greater than the thickness of the` nlm strip, whereby Ythe members 2| anclf22'v are spacedapart vto permit the'rilm strip to-be moved freely therethroughbut without any tendency to fold orbuckle' because `ofrexce'ssive clearance. 'The inner side edges of the strips' 29 areengaged by the side edges of thenlm strip S'to maintainthe latterin vertical alignment. Aswshown in Fig. 7; the members 2| and '22are each provided with a vertical recess 3l extending fromend 'toend and facingthe front and back offthe filmestrip'at the image "frames thereof to prevent the film' strip from rubbing against the guideway and damaging the emulsion.

'-"Inorder' to Lmaintain' the film strip perfectly flat at the point of projection and thereby mini; miie distortion of the projected image,V the memf bers 2| and122 have a recess 32 at leach side of their respective openings 24and 25 (Fig. 8)"n Whichethe side edges oi a pair of transparent plates'f3`4'farepositioned. Suitable flat springs vaie`mo'unted in the recesses 32 for urging the plates together, but the inner edges of the st rips ZQmaintain the plates `apart to permit free movement of the nlm strip' therebetween. ALA frame or mask v3I having'an opening corresponding to the aifea lof lthe image Vframes` to be projected is mounted between'the upper plate` 34 (as viewed in Fig. 8') and its springs,

V"If, desired, the frame 36 may be interchanged with otherfframes having openings correspondf ing to image frames of different areas. Thismis facilitated by reason of the detachablel connection between the members j2| and 22.'` Likewise,v the strips l25 may be interchanged with such strips o'fdiierent thickness to accommodate nlm strips of"d|fferent thickness.

Referring now to Figs. 3 to 7, there is shown mechanismmfor advancing the film strip through the'guideway just described,` preferably, one frame :at a time. This mechanismis Vmounted on the back of the front wall I2 (Figs. 3; 4, and v'7), and generallyv comprises a member 4Il slidably mounted in the slot I9 and riding on the backA of the body member 2| and a lever 4| pivotally mountedon the member 40 acting as a film strip engaging and advancing element which is rocked by the vhandle I5.

The slidable` member 4|)` may `be channeltending just loeloi/` the slot 2E 4and recess 2l..` The..

shaped with 'its open side facing the body member 2| and its anges riding thereon. A slot o1' opening 42 is formed in the Wall opposite its open side having upper and lower side edges 44 and 45, respectively, as viewed in Figs. 4 to 6, which serve as stops for the lever 4|, as described hereinafter.

'Ijhe lever 4| may be a bell crank which is pivotally mounted 'on a crosswise extending pin 46 carried by the channel member 4I! (Fig. 7), and which comprises an arm 41 extending through the opening 4j2 for cooperation with the stops 44 and 4.5V and a second arm 49 having a pointed portion 50 at its free end adapted to be moved intoslot ZIandrecess 21 of the members 2| and 22andenter theapertures or openings A of the film strip (Figs.4 5 to 7).

' The slidable member 40 is urged against the backof the body member 2| by resilient means, such as a flat spring 5I secured to the back of the wall, I2 (Figs. 3,and.7), whichspringhas a p ai'r of spaeedngers 52 straddlingthe opening 42 andengaging the'wall in which this openingl is' formed. Asshownin Fig. 7, the fingers-.52

l conform to thearcuate contour of thiswall thereby serve asbearing means for maintaining the'slidable member in vertical alignment. f

They handle I5 has oneend pivotally mounted on thebackofthe Wall Ifat 54 andhasatransf verse tabportion 55 at its other end tofacilitalt manual engagement thereofto depressthe-hanl dle. The handle is operatively connected toftle lever 4| by a link 55 having itsfends pivotally mounted on the Ahandle, and the leverl arm 4 1;- re-- r spectively. "The stroke of .the handlev is. determined by apairoffstops 51, and 59 wherbilfth nlm strip. will be advanced oneframe at a time', as'about`to be described..k As showninFigsQa and 7, the stop 5l limits the downward movement of the handle andtheV stop 59 limits theupward movement `of .the handle. Both stops lare shown formed. on a slidable, elongate element 58 preferablyior varying the range of Ythe Vhandle and4 the movement of the' film strip advancing elements.,

VAdVjdstment of theslidable element `5jmay`v be accomplished by loosely coupling the same Yto the lowerend of a rod extending through avl'oywer. bearing 6 I' and vscrew threaded through an upper bearing' ,621 (Fig. 3),. The upper end of this .rod has the knob I6 Ilsecured thereto for turningthe rod and causing4 the screw threaded bearing to eQ'Ct raising andlowerng of the Yelement 58 and the stops 'M51 and ,59NthereonQ lThe handle I5 "is preferably maintainedits normally upper or at restposition by a vsp ring,64` having litslunper end .connected to the back of the,- wall |2` and'havingits lower end connectedto the handle.

Inyoperatio'n, thegrilm strip. isinserted ,atA the. upper end `of the guideway with, its lowerV end.ex..

element 58 isthenpoitioned to adjust the stroke orirange` pf the vfilm strip advancing mechanism,v

to inoye thefilm strip downwardlyoneframe at ,a time, as vwell as. tocenter each frame with frespect to theopening I1.

The` elementsof the strip advancing mechanism normallyare in the position shown in Figs. 3 and 4, withthe handle I5 up, the lever arm.4l bearing against the ,upper` stop 44 and holding .the slid-- ablernernberqlq in its uppermost position, and the lever portionA V5|)outpf nlm engaging position. lllpqn initial downwardmovement of. the` handle the lever `4I is rocked to the `position.shown stop andthe'lever portion 50 extending into an aperture A of the film strip. Further downward movement of the handle causes the lever, by reason of its connection to the slidable member by means of the pin 46 and engagement of the stop 45 by the lever arm 41, to move downwardly together with the slidable member, whereby the lever portion 50 advances the film strip downwardly. The position of the elements at the end of such movement is illustrated in Fig. 6. When the handle is released, the spring 64 returns the same to its normal position. During such movement, the handle first rocks the lever upwardly to cause the portion 5D to be retracted and disengage the film strip and to cause its arm 41 to engage the stop 44, whereupon further upward movement of the handle causes the lever and the slidable member to be carried upwardly to the position shown in Fig. 4 with the lever portion 56 in position to engage the next aperture upon another operation of the handle.

In the event upon initial operation of the handle, an aperture of the lm strip is not aligned with the portion 50, the portion 50 rides along the film strip until it locates an aperture and then advances the film strip to a position whereby the next aperture will be in alignment with the portion 50 when returned to its upper position. In this manner, the advancing mechanism is self indexing.

During such an indexing operation, it will Ibe observed that the portion 50 would normally bear against the film strip to bend the portion thereof between the slot 26 and recess 21 out of its vertical path. Should the film strip for some reason resist such bending movement, the pointed end portion would bear against the film strip with considerable pressure and could dig into the iilm strip and tear or otherwise damage the same. This, however, is prevented by the spring 5I which is adapted to yield and permit slight movement of the slidable member 40 and the lever carried thereon towards the right (as viewed in Figs. 5 and 6), whereby the pointed end portion 56 slides along the lm strip Without inflicting damage thereto. Also, if for some unknown reason the film strip offers excessive resistance to movement, the spring 5| yields before the film strip is damaged.

From the foregoing description, it will be seen that the present invention provides a simple and practical film strip guideway and advancing mechanism for projectors which embodies adjustable or interchangeable elements enabling film strips of different sizes to be used in connection therewith. The apparatus is constructed of a minimum number of parts which can be economically manufactured and assembled. The advancing mechanism is reliable in operation, will not damage the film strip, is self indexing and can readily withstand such rough usage to which it may normally be subjected.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be noted that all matters are to be interpreted as illustrative and not in any limiting sense.

What is claimed is:

1. In a projector of the class described, the combination of a guideway for a strip of iilm which has an opening associated with each frame thereof, a member slidably mounted adjacent said guideway for movement longitudinally with re- 6., spect thereto and .having'a' pair of spaced, rigid stops, a lever pivotally mounted on said member having an arm positioned between said stops and having a second arm formed with an end portion for extending into the frame openings, and manually operable means connected to said level` for sequentially rocking said lever between said stops and then effecting movement of said slidable member upon engagement of one of said stops of said first mentioned arm.

2. A projector according to claim 1, wherein said slidable member is a. channel-shaped element formed with an opening through which said rst mentioned arm extends having opposite edges providing said stops.

3. A projector according to claim 1, wherein said lever is a bell crank having a pointed end portion at the free end of said second arm.

4. A projector according to claim 1, wherein resilient means engage said slidable member to maintain said member adjacent said guideway.

5. A projector according to claim 1, wherein said manually operable means include a pivotally mounted handle and linkage means connecting said first mentioned arm and said handle.

6. In a projector of the class described, the combination of a guideway for a strip of lm which has an aperture associated with each frame thereof, a channel-shaped member extending longitudinally with respect to said guideway with its open side facing said guideway and having an opening in the wall opposite its open side defining a pair of spaced stops, means for mounting said member for movement longitudinally with respect to said guideway, a bell crank pivotally mounted on said member for movement about an axis perpendicular to the longitudinal axis of said member, said bell crank having an arm extending through said opening for alternately engaging said stops and having a second arm formed with an end portion for extending into said frame apertures, a pivotally mounted manually operable handle, linkage means interconnecting said rst mentioned arm and said handle, a pair of stops for limiting the extent of movement of said handle, and a return spring connected to said handle.

'1. A projector according to claim 6, wherein said means for mounting said channel-shaped member include a leaf spring having a pair of spaced fingers engaging the wall of said member in which said opening is formed.

8. In a projector of the class described, the combination of a guideway for a strip of lm having an opening through which a beam of light is adapted to be projected and having a recess at the sides of said opening, a pair of transparent plates between which the film is adapted to pass having their outer edges positioned in said recess, a iiat member between said plates at the sides of said opening having a thickness slightly greater than the thickness of the iilm strip to space said plates apart just sufiiciently to enable the iilm strip to be moved freely therebetween, and means Y including flat springs mounted in said recess and engaging at least one of said plates adjacent opposite side edges thereof for maintaining said plates against said flat member.

9. In a projector of the class described, the combination of a pair of superimposed detachably secured members providing guideway means for a strip of film each having aligned openings through which a beam of light is adapted to be projected and each having a recess surrounding its opening, a pair of laterally spaced relatively LESTER RAYMOND BANGBBERJGH; 

